The Cardiff striker died while flying from his former club Nantes.

Emiliano Sala was exposed to harmful levels of carbon monoxide before he was killed in a plane crash and it is likely his pilot was also affected, accident investigators said.

Tests on the Cardiff striker’s body found enough evidence of the harmful gas to cause a heart attack, seizure or unconsciousness, an interim report by the Air Accidents Investigation Branch (AAIB) stated.

The cockpit of the Piper Malibu aircraft involved in the crash was not separated from the cabin and it is “likely” that pilot David Ibbotson was also “affected to some extent” by exposure to carbon monoxide, the document added.

(PA Graphics)

The AAIB said the gas can “reduce or inhibit a pilot’s ability to fly an aircraft depending on the level of that exposure”.

The Argentinian, who was 28, signed for Cardiff City from French club Nantes for £15million on January 18.

Mr Ibbotson, 59, of Crowle, Lincolnshire flew Sala from Cardiff to Nantes the following day.

The return flight – which crashed in the Channel – was on January 21.

Sala’s body was recovered on February 6 but Mr Ibbotson has not been located.

A woman looks at the tributes at Cardiff City Stadium (Aaron Chown/PA)

The aircraft remains underwater off the coast of Guernsey after an attempt to recover it was hampered by bad weather.

The AAIB said it was working with the aircraft and engine manufacturers and the National Transportation Safety Board in the US “to identify possible pathways through which CO might enter the cabin of this type of aircraft”.

The report added: “Work is also continuing to investigate pertinent operational, technical, organisational and human factors which might have contributed to the accident.”

Daniel Machover of Hickman and Rose solicitors, lawyers for Sala’s relatives, said the presence of carbon monoxide “raises many questions for the family”.